Combo photo taken on May 3, 2020 shows Cao Xiongbin checking the temperature of his colleague (left) and posing for a photo at the construction site of the Renhuai-Zunyi expressway in Zunyi, southwest China's Guizhou Province. Cao, 25, from Jingdezhen of Jiangxi Province, has been working as a staff member on the COVID-19 control and prevention since early time this year. Many young workers have stuck to their positions during Labor Day holiday. (Xinhua/Liu Xu)